1. Field of the Invention
The present invention relates to a non-halogen resin composition, an insulated electrical wire having a conductor and an insulated layer disposed over a circumference of the conductor and formed of the same non-halogen resin composition, and a wire harness comprising the same insulated electrical wire.
2. Description of the Related Art
Conventionally, an insulating electrical wire arranged in a vehicle has been prepared by covering a copper wire with a resin composition comprising polyvinyl chloride resin as a base resin component. This resin composition is generally referred as a “PCV resin composition”. Since the polyvinyl chloride resin is self-extinguishing material, it achieves high level of flame retardant property. In addition, the hardness of the polyvinyl chloride can be easily controlled by the addition of a plasticizer thereto. Furthermore, the polyvinyl chloride resin achieves high level of abrasion resistance. Meanwhile, it is disadvantageous that the polyvinyl chloride resin can produce harmful or noxious halogen gas during or after its incineration process, thus exerting a bad influence on environment.
To overcome the afore-mentioned disadvantage, a polyolefin-based non-halogen resin composition has been deeply researched and developed. Japanese Publication of Patent Applications No. 2003-313377, 2007-56204 and 2007-63343 are directed to such a polyolefin-containing non-halogen resin composition. In such polyolefin-containing non-halogen resin composition, flame retardant property was enhanced by the addition of an inorganic flame retardant component such as metal hydroxide thereto.
However, to achieve a desired level of flame retardant property, inorganic flame retardant component should be added in a large amount to the non-halogen resin composition. In this case, the flame retardant component contained in the resin composition generally exerts a negative impact on the mechanical properties such as abrasion resistance, flexibility, heat resistance performance, and etc. of the final non-halogen resin composition.
Currently, in order to prepare an insulated electrical wire, a conductor is generally covered with the non-halogen resin composition. However, in a wire harness, above insulated electrical wire whose conductor is covered with the non-halogen resin composition is generally used together with an insulated electrical wire whose conductor is covered with the conventional PCV resin composition. As the case may be, two different insulated electrical wires are bound together. In this case, there is problem that the plasticizer contained in the PCV composition generally migrates from the insulating layer formed of PCV composition to the insulating layer formed of the non-halogen resin composition over time, thus causing long-term heat resistance to be remarkably lowered or deteriorated.
The present invention is provided to solve the afore-mentioned problems. In other words, the present invention provides a non-halogen resin composition comprising an inorganic flame retardant, and achieving remarkably enhanced level of mechanical properties such as abrasion resistance, flame retardant property, flexibility, and long-term heat resistance. Also, the present invention provides an insulated electrical wire having a conductor and an insulating layer disposed over a circumference of the conductor and formed of the afore-mentioned non-halogen resin composition in accordance with the present invention, and a wire harness comprising at least one insulated electrical wire in accordance with the present invention.